What I will refer to as 'HTML5 Storage' is a specification named Web Storage, which was at one time part of the HTML5 specification proper, but was split out into its own specification for uninteresting political reasons. Certain browser vendors also refer to it as 'Local Storage' or 'DOM Storage.' Simply put, it's a way for web pages to store named key/value pairs locally, within the client web browser. Like cookies, this data persists even after you navigate away from the web site, close your browser tab, exit your browser, or what have you. Unlike cookies, this data is never transmitted to the remote web server (unless you go out of your way to send it manually). Unlike all previous attempts at providing persistent local storage, it is implemented natively in web browsers, so it is available even when third-party browser plugins are not. (Excerpt from this source)